#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int a,b,c,d,e;
	float aver;
	scanf("%d %d %d %d %d", &a,&b,&c,&d,&e);
	aver = (a + b + c + d + e) / 5.0f;
	printf("%0.1f\n", aver);
	return 0;
}